ABSTRACT Employee internal and external networking behaviours may drive different employee and organisational outcomes, which has implications for Human Resource Development professionals. However, little is known about how to develop internal and external networking behaviours. Using social role theory, social capital theory, and personal initiative theory, this study examines the impact of employee gender, education, political skills, and mentoring on internal and external networking behaviours. We utilised a mixed-method sequential research design comprising two studies. Study 1 survey data were collected from 372 middle managers from 10 Sri Lankan manufacturing and service organisations. The results indicate the higher external networking behaviours of men; the elevated internal and external networking behaviours of managers with a master’s degree; a positive relationship between political skills and both internal and external networking behaviours; and a positive relationship between mentoring and internal networking behaviours. Study 2 comprised 12 interviews of middle managers who had participated in Study 1. Thematic and content analyses explain, refine, and extend the results of Study 1. The findings have several implications for developing the networking behaviours of middle managers. Theoretical and research contributions are discussed.